The developer mix in a xerographic copier contains two elements, toner and steel beads. The steel beads act as carrier for the toner so that magnetic transport rollers and magnetic brush rollers can move the toner to the photoconductor. At the photoconductor, some of the toner transfers from the steel beads to the electrostatic image on the photoconductor to develop that image.
As toner is used up in the developing process, additional toner is metered into the developer. After many thousands of copies, the developer mix begins to degrade even though it is being replenished with fresh toner. When this occurs, substantially all of the developer mix must be removed from the developer and replaced with a new developer mix.
Replacing the developer mix has been a time consuming and dirty job. Typically, the entire developer is removed from the machine and held upside-down over a trash container to dump the old developer mix. The customer engineer performing this task must wear gloves or be prepared to have his hands covered by black toner dust. Even if a vacuum cleaner is used on the developer, it is difficult to remove the old mix because the particles in the mix are electro-statically charged.
Another way to purge the developer mix involves exposing the magnetic brush roller, placing a scraper with catcher against the surface of the roller and rotating the magnets within the roller. The magnetic brush is exposed by sliding the developer on rails out the side of the copier. A scraping blade with a catching container is then held against the surface of the magnetic brush roller. A handle for rotating the magnetics about a shaft inside the roller is pulled out and turned by the operator. As the magnets rotate within the roller, the developer mix walks along the surface of the roller and is scraped off into the catching container by the scraping blade.
Yet another technique for purging developer mix consists of opening a front wall of the developer and attaching a catching container to the opening. The catcher has a lever operated deflector. Once the catcher is attached, the lever is rotated so that the deflector enters the developer and moves into the return path for the mix from the magnetic brush to the mixing sump at the bottom of the developer. Now as the developer is operated, the deflector intercepts the mix and deflects it into the catcher.
While the above techniques accomplish the dumping of the developer mix, they still are likely to leave residual mix in the developer and cause some toner contamination of the copier or the operator. In one case, the operator must hold a scraper against the magnetic brush roller and, in the other case, the operator must open up the developer before the catcher is attached.